How to justifiy playing the classic old Wizard trope when the game starts at Level 1

Struggling to come up with backstory that fits around the type of character i want to play being that of an Old well studied wizard given this campaign starts at level one. I feel it does not make a lot of sense for the character to be of a low level given the base character im wanting to play.

Some ideas ive floated around include Magical Dementia, bookworm who never bothered with the practical aspects, being old enough to have been born before the spell plague and now hes having to re learn everything, but timeline wise this may not make any sense unless i go with an Elf as Spellplague is just over 100 years ago.

Any other ideas you folks could think of to help me out would be appreciated as I like to flesh out my characters and make them make sense.